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Rupture process and near‐source shaking of the 1965 Seattle‐Tacoma and 2001 Nisqually, intraslab earthquakes

2004; American Geophysical Union; Volume: 31; Issue: 10 Linguagem: Inglês

10.1029/2004gl019668

1944-8007

G. A. Ichinose, H. K. Thio, Paul Somerville,

Seismic Waves and Analysis

We inverted teleseismic data for the 1965 Seattle‐Tacoma earthquake slip and rake. The earthquake had 2 asperities of 12 and 16 km 2 near the hypocenter with average slip of 2 and 2.8 m respectively (M o = 9.4 × 10 25 dyne‐cm; M w = 6.6). We also inverted strong‐motion and teleseismic data for the 2001 Nisqually earthquake. This earthquake had 2 subevents with an asperity area of 45 km 2 between 59 and 62 km depth with an average slip of 1.7 m (M o = 1.7 × 10 26 dyne‐cm; M w = 6.8). Shake‐maps of peak ground acceleration (PGA) and spectral acceleration (S a ) were generated using a time‐domain approach including slip model, site, and basin‐depth corrections based on California geology. Corrections reduced the residuals between observed and predicted PGA and S a . The simulated pattern of shaking from the 1965 earthquake was twice as high as in the 2001 earthquake due to the proximity of the 1965 epicenter to sedimentary basins.